Oligoryzomys chacoensis (Myers and Carleton, 1981) . Mise. Pubi. Mus. Zool., Univ. Michigan, 161: 19.

TYPE LOCALITY: Paraguay, Boqueron Dept., km 419 along Trans Chaco Hwy, northwest of Villa Hayes .

DISTRIBUTION: Dryer habitats of W Paraguay, SE Bolivia, WC Brazil, and N Argentina. May be more broadly distributed in cerrado and caatinga habitats in SE Brazil.

COMMENTS: Karyotype reported by Myers and Carleton (1981); morphometric variation by Myers and Carleton (1981) and Olds and Anderson (1987). Status with regard to O. andinus unresolved.